Hi,
can you explain in detail about how you are planning to connect 16 ADC-DAC to the processor? I don't think you can connect 16 ADCs to SPORT1_A and 16-DAC's to SPORT1_B.
About limitations of using SPMUX when ACM is enabled:- if ACM_EN is high, the mux select bits FSMUXSEL, CKMUXSEL are ignored at the SPORT which is configured to connect with ACM. This is obvious, because that SPORT will receive clock and FS from ACM; so it cannot accept CLK/FS from paired SPORT half.